1. Field of the Invention
The present invention relates to a method, and an apparatus to perform the method, of encoding and/or decoding multi-channel signals, and, more particularly, to a method, and an apparatus to perform the method, of encoding multi-channel signals according to the similarity among multi-channel signals, and a decoding method and apparatus therefor.
2. Description of the Related Art
In modern telecommunication technologies, most products and processes are changing from analog to digital technologies. In line with this trend, digital transmission has become essential in a vast majority of audio apparatuses and/or audio transmission. The transmission of digital audio signals is more robust against environment noise than that of conventional analog signals. Thus, transmitted digital audio signals can be reproduced with sound quality as clear as digital audio signals reproduced from a compact disc (CD). However, since the amount of data required to be transmitted has constantly increased, many problems, such as the storage capacity of a medium to store data and transmission lines, have arisen.
Data compression is one technology that can be used to alleviate these problems. In an audio compression received after an original audio signal is compressed and transmitted, the quality of the reproduced audio signal is almost the same as that of the original audio signal. That is, audio compression enables the transmission of a smaller amount of information per time unit while ensuring nearly the same quality level of a reproduced audio signal that is not compressed.
Compared to a mono audio signal, which is provided through one channel, a stereo audio signal, which is a combination of audio signals respectively provided through a plurality of channels, enables listeners to enjoy stereo sound.
However, since the stereo audio signal is a combination of mono audio signals obtained from a plurality of channels, storing or transmission of stereo audio signals is more difficult and expensive than that of mono audio signals. This is because when each channel signal of mono audio signals respectively obtained from a plurality of channels is independently encoded, the amount of data increases by a factor of the number of channels. The amount of data can be reduced by reducing the sampling rate or employing lossy encoding, but the sampling rate directly affects the sound quality, and the lossy encoding may also be a factor for the degradation of sound quality.
Accordingly, a method of encoding and decoding multi-channel signals by effectively removing redundant information among channels without directly affecting the sound quality is needed.